diff --git a/README.md b/README.md
index 694f94d..1b33ebb 100644
--- a/README.md
+++ b/README.md
@@ -71,16 +71,7 @@ Installation
     Generate and prepare a PEM certificate file.
     ```sh
     $ cd ~/bluepy-scratch-link
-    $ openssl req -x509 -out scratch-device-manager.cer \
-    -keyout scratch-device-manager.key -newkey rsa:2048 -nodes -sha256 \
-    -subj '/CN=scratch-device-manager' -extensions EXT -config <( \
-    printf "[dn]\nCN=localhost\n[req]\ndistinguished_name = dn\n[EXT]\nsubjectAltName=DNS:localhost\nkeyUsage=digitalSignature\nextendedKeyUsage=serverAuth")
-    $ openssl pkcs12 -inkey scratch-device-manager.key \
-      -in scratch-device-manager.cer \
-      -name "Scratch Link & Scratch Device Manager" \
-      -passout pass:Scratch -export -out scratch-device-manager.pfx
-    $ grep -h ^ scratch-device-manager.cer scratch-device-manager.key \
-      | tr -d '\r' > scratch-device-manager.pem
+    $ ./gencert.sh
       ```
 
 6. If using a micro:bit, install Scratch-link hex on your device
diff --git a/gencert.sh b/gencert.sh
index 7143ba3..bedf02f 100755
--- a/gencert.sh
+++ b/gencert.sh
@@ -1,6 +1,12 @@
-openssl req -x509 -out scratch-device-manager.cer \
--keyout scratch-device-manager.key -newkey rsa:2048 -nodes -sha256 \
--subj '/CN=scratch-device-manager' -extensions EXT -config <( \
-printf "[dn]\nCN=localhost\n[req]\ndistinguished_name = dn\n[EXT]\nsubjectAltName=DNS:localhost\nkeyUsage=digitalSignature\nextendedKeyUsage=serverAuth")
-grep -h ^ scratch-device-manager.cer scratch-device-manager.key \
-  | tr -d '\r' > scratch-device-manager.pem
+#!/bin/bash
+openssl req -x509 -out scratch-device-manager.pem \
+	-keyout scratch-device-manager.pem -newkey rsa:2048 -nodes -sha256 \
+	-days 3650 -extensions EXT -config /dev/stdin << HERE
+[dn]
+CN = device-manager.scratch.mit.edu
+[req]
+prompt = no
+distinguished_name = dn
+[EXT]
+subjectAltName = DNS:device-manager.scratch.mit.edu
+HERE